Added Chapter on File Handling

[logananglin98]

Creating a draft pull request as this code still has some problems.

None of the Python code is interactive because it uses the os library, which can't be used within the book.

I am unable to test the Java code. It is interactive for now, but I would imagine it may not function as intended considering it handles files. All completed Java code was tested in an online compiler and functions as intended.

The name of the pretext file is "ch_x_filehandling.ptx". It will appear as chapter 8 if the book is built because that is where I listed it in main.ptx (chapter 8 will be 9, chapter 9 will be 10, and so on). I figured this was a good place to put the chapter, but other locations may be good as well. We considered that it may be better to wait to determine a final location and rename the other chapter file names after other issues that add chapters and condense chapters are taken care of, but it may be a good idea to go ahead and make the necessary file name changes.

Please let me know any changes that may be desired!

[pearcej]

This looks really good, but I suspect we can actually use active code as long as the file has been uploaded and is accessible. It will be hard for me to review this way and much harder for students to learn from.

Please look in the pretext guide first maybe starting here: https://pretextbook.org/doc/guide/html/topic-datafile.html
If you don't find it, ask in the author channel on Discord.

[pearcej]

I am accepting this because it is a significant improvement.

However, there is still room for significant improvements. Some sections have no mention of Python at all. Since this is a transition book, we need to give students an understanding of how to bridge to Java. If Python's libraries are going to be automatically available, this should be said!